APPARECCHIO A RACLE PER SAGOME PIATTE, CON DUE DISPOSITIVI PORTA RACLA DISPOSTI A DISTANZA FRA LORO

An apparatus for printing a pattern of a flat horizontal screen on an underlying substrate comprises a wiper assembly mounted on a carriage above the screen and an electromagnet beneath the screen reciprocable along the latter jointly with the carriage. A cradle limitedly pivotable on the carriage about a horizontal axis extends across the screen and supports, via adjustable holders, a working wiper and a distributing wiper on opposite sides of its pivotal axis. The working wiper, which may be a blade or a roller, directly overlies the electromagnet and is magnetizable and/or accompanied by a magnetizable mass whereby energization of the electromagnet attracts the side of the cradle bearing that wiper to press it against the screen for forcing dyestuff therethrough onto the substrate, this side trailing during a printing stroke. When the electromagnet is de-energized at the end of that stroke and motion is reversed, with the screen and the carriage lifted off the substrate, the relatively heavy distributing wiper causes a tilt in the opposite direction and contacts the screen to spread the residual dyestuff thereover during the return stroke. When the working wiper is a magnetically permeable roller, a permanent magnet on its holder-weaker than the energized electromagnet-attracts that roller upward during de-energization.